Scanning of large objects, e.g. large maps or technical drawings, is conventionally performed by use of a plurality of scanner cameras as it is difficult and expensive to manufacture image sensors with dimensions sufficiently wide to cover a large document such as an A2 format, A1 format or A0 format. Examples of image sensors are charge coupled devices (CCD) or contact image sensors (CIS). The image sensors are typically arranged on a movable fixture, moving past a medium to be scanned, or the medium is pulled past the fixture by means of motor-operated rolls.